The present invention deals with an improved tapered core chuck for hollow cores, particularly as used with rolls of paper, but not limited thereto.
In the paper, printing and allied industries, paper or other sheet material in web form is usually handled in the form of rolls of the material that is wound onto hollow fiber or plastic cores. These cores usually have a notch or key opening in one or both ends for engagement with a key or keys that are mounted on the core chucks or plugs which fit into the ends of the core. The cores in this condition can thus be used for winding or unwinding the material. However, with the typical fiber cores normally used in the paper industry, more often than not the core ends are damaged or the key slots are multilated which renders the conventional keyed, tapered core chuck unsatisfactory for keeping the core firmly in place during winding and unwinding. In addition, the cores are generally not precisely sized so that the internal diameter of the cores from unit-to-unit varies, further complicating the ability to get the cores fixed on the standard sized core chucks.
To overcome these problems, a number of different alternatives have been proposed including expanding chucks, tapered chucks with fluted surfaces and chucks with internal locks which tilt into locked position. However most of these efforts have resulted in core chucks that are quite expensive, difficult to maintain and use, and very simply not completely satisfactory in performance.
Examples of some of the prior art core chucks are exemplified in the following list of U.S. Pat. Nos.
1,402,060 PA1 2,922,592 PA1 3,368,769 PA1 3,704,837
As will be seen from studying the above noted U.S. Pat. Nos. 1,402,060, 2,922,592 and 3,704,837 each work on the principle whereby the core locking devices are forced into position automatically by mechanical action as the core is inserted on the chuck, while applicant's prior U.S. Pat. No. 3,368,769, uses a floating key arrangement for accomodating different sized cores. In contrast to these and other prior art core chucks, the core chuck of the present invention utilizes chuck dogs that are normally spring biased into a retracted condition, but which can be engaged into the hollow core by a separate mechanical action not inherent with the placing of the core on the chuck. Moreover, it will be seen that the core chuck of the present invention is particularly useful with damaged cores and further satisfies a need for a simple and expedient device of rugged construction.